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Joined: Apr 2002
Posts: 914
Hey Guys, I know this is common knowlege to many of you, but I need a little help.
I've got a shopping center sign that we went to repair and ran into a problem we couldn't easily fix. It's a huge sign with several sections. Most were fixed with new bulbs or a ballast, but we couldn't get one sections working 100%. Actually we only got it 20%. It has 5 6ft High Output bulbs and a USB 1232 ballast. We tried bulbs first, then a new ballast and still could only get 1 buld to fire. What else is there to check? One socket was questionable, but with that ballast the other bulbs should still work. If the ballast is working properly what should a meter read on each socket? What is the best way to find the problem? Any help is appreciated.

Joined: Jul 2002
Posts: 680
Not familar with that ballast but the oil company signs I work on, the bulbs seem to be in series. One bulb out and others will be out also. I've seen many bad bulbs right out of the box and in my case one bad socket will keep the sign from lighting completely.

Joined: Aug 2003
Posts: 99
If you try bulbs that work in other sockets and it is still no-go, then it could be a loose connection on the sockets. You could try to get continuity between the socket and the wire, and then move the wire gently to see if that is it. If that isn't it, then you could have a bad ballast. Of course this assumes that you have checked for your line voltage.

Joined: Apr 2002
Posts: 7,305
Likes: 6
HO sockets (sign type) are notorious around here for corrosion. A 'bad' contact between the socket contacts and the bulb can be a real pain. Next on the 'list' is socket spring tension. Then, secondary wiring failure; usually in the 'raceways' behind the sockets, where ya can't see it until you take ita all apart.

We have a few that use F120 HO (10' bulb), one ballast, 4 bulbs; one lamp out, all are out. Sure wish the mfg did the "one out; balance lit" thing for HO sign ballasts.

Signs can be a real "PAIN" or a "good gain"

PS; The secondary voltage should be printed on the ballast label.

Good Luck


Joined: Dec 2004
Posts: 5
Junior Member
If you have 1 lamp lit only on a five lamp ballast, you either have a bad ballast,(but you've replaced it and odds are slim that a new ballast would the same exact malfunction), or you have secondary wiring that is going to ground.When I prepare to replace an outdoor sign ballast, I cut the secondary leads 6" or so from the ballast, remove all the lamps,and use my Extech digital insulation tester (around two hundred bucks from Grainger a few years ago,although they no longer carry it, but I saw Mitchell Instrument still does),and check all the secondary leads to ground.
I would bet that there is a wire either one of the yellows or one of the browns that is burnt or pinched and most likely in the bottom part of the sign.If that yeilds no answer, try using a continuity tester on each pair of leads, (the end of the H.O. lamp stuck into the sockets one at a time will provide a "jump" between the two recessed double contacts in the socket),mark by each socket which pair of wires goes where,and compare that to the label on the ballast to ensure it is wired correctly.
I hope my methods are understandable, please let us know what the results are


Joined: Jan 2004
Posts: 79
First, rotate known good lamps from one of the good sections to make sure you don't have any bum lamps. Next, you'll have to open the socket troughs to look for secondary shorts or faults to ground. Then, change that ballast which could be bad from the me, not far fetched. Also, don't be surprised if the person who wired the previously ballast wired it wrongly. Most of the time, a six-lamp combination ballast is used for a five-lamp configuration and some of the lamp leads are capped off per the wiring diagram on the label. I'd double check the secondary wiring.
Hope this helps,

BTW, the model #1232 probably means its a 4-5-6 lamp combination ballast for 12' to 32'. So, (5) 6' lamps (F72T12 H.O.'s) equals 30' total lamp footage, which should be the correct ballast. If the lamps are vertical, check the bottom socket troughs first since rain water will travel south down the lamps to the bottom sockets to cause ground faults, shorts and general havoc.

[This message has been edited by cavo148 (edited 05-28-2005).]

Joined: Apr 2002
Posts: 914
Thanks Guys.

Cavo, it sounds like you've got experience with this same set up. You're probably right about the water, 1 of the bulbs actually had 6" of water in the bulb. Not sure how that happened. Do you know how to test the ballast output at the socket? What should each socket read? Thanks.

Joined: Jan 2004
Posts: 79
Eagle, I never got that scientific determining what was wrong with any sign ballasts. Usually, it's bad lamps or ballast. Shorts are very, very common in signs because they're never really watertight. Vertical is a bad position for lamps in signs because water will enter eventually, travel down the lamps to the bottom sockets and well up. One socket can knock out the rest, usually on the red lamp leg as I remember, so I'd change any burnt ones.
That 6" of water in the lamp got there via a heat crack in the glass at the bottom of the socket most likely. The lamp has negative pressure, a vacuum, and literally sucked up the cool water that cracked the glass to begin with. The ends of the lamps get hot and when cool water comes into contact it fractures.

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